Radial cam helix with 0 degree stow for solar tracker

ABSTRACT

A solar tracking system including a plurality of bases, a torque tube supported by the plurality of bases and configured to support a plurality of solar modules, and a drive device operably connected to the torque tube and arranged to translate the torque tube in a direction parallel to its longitudinal axis. The solar tracking system also includes a plurality of helical guides operably connected to the torque tube, and a plurality of cam assemblies, wherein upon linear movement of the torque tube, interaction between the helical guides and cam assemblies causes the torque tube to rotate about its linear axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/357,782, filed on Jun. 24, 2021, which is a continuation of U.S.application Ser. No. 16/418,433 filed May 21, 2019, now U.S. Pat. No.11,050,383, the entire contents of each of which are hereby incorporatedby reference.

BACKGROUND Technical Field

The present disclosure relates to solar systems, and more particularly,to solar tracker actuating systems for adjusting the orientation of thesolar system to track the location of the sun.

Description of Related Art

Solar cells and solar panels are most efficient in sunny conditions whenoriented towards the sun at a certain angle. Many solar panel systemsare designs in combination with solar trackers, which follow the sun'strajectory across the sky from east to west in order to maximize theelectrical generation capabilities of the systems. The relatively lowenergy produced by a single solar cell requires the use of thousands ofsolar cells, arranged in an array, to generate energy in sufficientmagnitude to be usable, for example as part of an energy grid. As aresult, solar trackers have been developed that are quite large,spanning hundreds of feet in length.

Adjusting massive solar trackers requires power to drive the solar arrayas it follows the sun. As will be appreciated, the greater the load, thegreater the amount of power necessary to drive the solar tracker. Anadditional design constraint of such systems is the rigidity required toaccommodate the weight of the solar arrays and at times significant windloading.

Further, the torsional excitation caused by wind loading exertssignificant force upon the structure for supporting and the mechanismsfor articulating the solar tracker. As such, increases in the size andnumber of components to reduce torsional excitation are required atvarying locations along the length of the solar tracker. The presentdisclosure seeks to address the shortcomings of prior tracker systems.

SUMMARY

The present disclosure is directed to a solar tracking system includinga plurality of bases, a torque tube supported by the plurality of basesand configured to support a plurality of solar modules, and a drivedevice operably connected to the torque tube and arranged to translatethe torque tube in a direction parallel to its longitudinal axis. Thesolar tracking system also includes a plurality of helical guidesoperably connected to the torque tube, and a plurality of camassemblies, wherein upon linear movement of the torque tube, interactionbetween the helical guides and cam assemblies causes the torque tube torotate about its linear axis.

The drive device may include at least on power screw. And the helicalguide may include a cam follower which mates with and follows one ormore cams in the cam assembly. The cam follower may include a stowposition portion. The stow position portion may corresponds to a0-degree stow position wherein solar modules supported by the torquetube are substantially parallel to the ground.

The cam assembly may include a pair of cams, and the cam follower actson the two cams to cause the rotation.

In the solar tracking system of the present disclosure, when driven tothe 0-degree stow position, substantially all forces applied to thetorque tube are translated through the cam follower, to the cams and tothe plurality of bases.

The helical guide may include a body, a cam follower, and a plurality offlanges. The helical guide may be mechanically fastened to the torquetube and can include a plurality of webs.

The cam follower may be welded on a backside of the cam follower tostrengthen the cam follower. Further, the helical guide may be formed oftwo parts, where each part has flanges and holes configured formechanical connection to at least two orthogonal surfaces of the torquetube.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and features of the present disclosure are describedhereinbelow with reference to the drawings, wherein:

disclosure;

FIG. 1 is a perspective view of a solar tracking system in accordancewith the present

FIG. 2 is a second perspective view of the solar tracking system inaccordance with the present disclosure;

FIG. 3 is an end view of the solar tracking system in accordance withthe present disclosure in a first position;

FIG. 4 is an end view of the solar tracking system in accordance withthe present disclosure is a second position;

FIG. 5 is a perspective view of a drive mechanism of the solar trackingsystem in accordance with the present disclosure;

FIG. 6 is a side view of a solar tracking system in accordance with thepresent disclosure;

FIG. 7 is a perspective view of a helical drive mechanism in accordancewith the present disclosure;

FIG. 8 is a side view of the helical drive mechanism in accordance withthe present disclosure;

FIG. 9 is a back-side view of a helical guide device in accordance withpresent disclosure; disclosure;

FIG. 10 is a front-side view of a helical guide device in accordancewith present

FIG. 11 is a close-up view of a portion of the helical guide device inaccordance with the present disclosure.

DETAILED DESCRIPTION

One of the issues with wind loading of solar trackers is back driving.That is as the solar tracker is wind loaded, the wind can actuallyovercome the friction forces of the system and the driver (when notrunning) and allow the solar tracker to be forced beyond a desiredposition. As one of skill in the art will recognize, past a certainangle to the direction of the wind, the solar modules again act as asail and being applying force against the driver, which causes this backdriving. Without preventing back driving, the solar tracker coulduncontrollably back drive and damage the solar modules or othercomponents. To prevent back driving, many systems employ drive devicesthat have very high angle threads, they employ wind dampers, or othermechanisms which largely resist back driving. However, these systemscome at a decided cost.

The present disclosure is directed to solar tracking systems and methodsfor articulating a solar tracking system. More specifically, the presentdisclosure is directed to a helically driven solar tracker. To enablehelical drive of a solar tracker, a linear drive including one or moredrive screws may be placed on one end of the solar tracker or in themiddle of solar tracker. The linear drive moves the solar trackerlinearly in a north-south direction. As the solar tracker is driven in anorth-south direction, the torque tube rotates as it follows a helicalguide mechanism. Further, as presented herein, the helical guidemechanism may be employed to minimize the amount of force that istranslated back to a drive device, when the tracker is placed in a stowposition.

Embodiments of the present disclosure are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views. In thedrawings and in the description that follows, terms such as front, rear,upper, lower, top, bottom, and similar directional terms are used simplyfor convenience of description and are not intended to limit thedisclosure. In the following description, well-known functions orconstructions are not described in detail to avoid obscuring the presentdisclosure in unnecessary detail.

With reference to FIGS. 1-11 , a solar tracking system capable oftracking the location of the sun provided in accordance with the presentdisclosure and is illustrated and generally identified by referencenumeral 10. The solar tracking system 10 includes a solar array 20, aplurality of support beams 30 configured to support the solar array 20,a plurality of torque tubes 40 configured to support the plurality ofsupport beams 30, a plurality of bases 50 configured to rotatablysupport the plurality of torque tubes 40, and drive mechanism 100 (FIG.4 ) that is configured to rotate the plurality of torque tubes 40, andtherefore the solar array 20, relative to the plurality of bases 50.

As illustrated in FIG. 1 , the solar array 20 may be broken up into afirst portion 20 a and a second portion 20 b, where the first and secondportions 20 a, 20 b are spaced apart from one another along the lengththereof defining a gap 20 c therebetween. Each portion of the first andsecond portions 20 a, 20 b is substantially similar, thus, only thefirst portion 20 a will be described in detail hereinbelow in theinterest of brevity. The first portion 20 a of the solar array 20includes a plurality of photovoltaic modules 22, each of which ismechanically and electrically coupled to one another, although it iscontemplated that each photovoltaic module 22 may be mechanically and/orelectrically insulated from one another. The photovoltaic modules 22 maybe any suitable photovoltaic module capable of generating electricalenergy from sunlight, such as monocrystalline silicon, polycrystallinesilicon, thin-film, etc. The photovoltaic modules 22 define an uppersurface 22 a and an opposite, bottom surface 22 b. As can beappreciated, the upper surface 22 a of the photovoltaic modules 22includes the photovoltaic cells (not shown) while the bottom surface 22b includes any suitable means for fixedly or selectively coupling thephotovoltaic modules 22 to the plurality of support beams 30, such asmechanical fasteners (e.g., bolts, nuts, etc.), adhesives, welding, etc.In embodiments, the photovoltaic cells may be disposed within a suitableframe 22 c (FIG. 3 ) which includes suitable means for fastening thephotovoltaic modules 22 to the plurality of support beams 30. In thismanner, the frame 22 c may include fastening means on a bottom surfacethereof, or clamps or other suitable fasteners (e.g., Z-brackets,C-clamps, angle brackets, etc.) may be utilized to abut a portion of theframe 22 c and selectively or fixedly couple the frame 22 c to theplurality of support beams

Each tube of the plurality of torque tubes 40 is substantially similarand, thus, only one torque tube 40 will be described in detailhereinbelow in the interest of brevity. The torque tube 40 defines agenerally tubular configuration having a generally square profile,although it is contemplated that the torque tube 40 may have anysuitable profile, such as rectangular, circular, oval, etc.

Turning to FIG. 3 , each base of the plurality of bases 50 issubstantially similar and, thus, only one base 50 will be described indetail hereinbelow in the interest of brevity. The base 50 is showngenerally as being an I-beam, although it is contemplated that anysuitable type of beam may be used, such as a U-channel, Box tubes, roundtubes, etc. Each base 50 includes a first end portion 50 a that isconfigured to be anchored in the ground or to a stationary object and asecond, opposite end portion 50 b that is configured to couple to aportion of the torque tube 40. It is contemplated that the base 50 maybe formed from any material suitable for use outdoors and groundcontact, such as steel (e.g., galvanized, stainless, etc.), aluminum,composites, polymers, etc. The comparison of FIG. 3 to FIG. 4 shows thechance in position of the solar tracker 10 as the solar array 20 isrotated relative to the bases 50. Thought only showing movement in onedirection, one of skill in the art will recognize that the solar array20 may also be driven in the opposite direction, and that the positionof the solar array 20 is predominately determined based on the angle ofthe sun to the solar array 20 to maximize collection of solar energy.

FIG. 5 depicts a drive mechanism 100. The drive mechanism 100 issupported by a base 50 and includes a gearbox 102, a power screw 104,and a motor 106. The gearbox 102 includes a housing 108 having athrough-bore defined through opposing side surfaces thereof. Thethrough-bore configured to rotatably retain a portion of the power screw104 therein. The housing 108 also receives the motor 106. The gearbox102 is to the base 50 using any suitable means, such as brackets,welding, adhesives, etc.

The power screw 104 extends between a first end portion 110 a and asecond, opposite end portion 110 b and has a threaded outer surface 104a adjacent the first end portion 110 a and a second threaded outersurface 104 b adjacent the second end portion 110 b. The first andsecond threaded outer surfaces 104 a, 104 b may be separated by anunthreaded or incomplete threaded center portion interposedtherebetween. Each of the first and second threaded outer surfaces 104a, 104 b defines a different thread direction (e.g., opposite oneanother), such that the first threaded outer surface 104 a may define aright-hand thread whereas the second threaded outer surface 104 b maydefine a left-hand thread, or vice versa. As can be appreciated, each ofthe first and second threaded outer surfaces 104 a, 104 b define athread direction that is complementary to the drive direction of threaddirection of respective threaded bores of the end caps 112, which areinserted into the torque tubes 40, such that the power screw 104 drivesmay engage the threaded bores. In this manner, as the power screw 104 isrotated in a first direction, the first and second threaded end caps 112are drawn towards one another to reduce the gap between the two torquetubes 40 and as the power screw 104 is rotated in a second, oppositedirection, the two torque tubes 40 are pushed away from one another toincrease the gap. As will be described in further detail hereinbelow,the axial translation of the two torque tubes 40 results in helicalrotation of the torque tubes 40 and the solar modules 22 attachedthereto.

FIG. 6 depicts the drive mechanism 100 supported on a cross-beam 52spanning two bases 50. This arrangement provides more support for thedrive mechanism and the solar tracker 10 proximate the drive mechanism.In FIG. 6 , the solar array 20 has been rotated away from the viewer toa position similar to that depicted in FIG. 4 . As noted above, ratherthen being placed in the gap 20 c between solar array portions 20 a and20 b, the drive mechanism may be placed on just one end of the solararray 20. In such an arrangement the system my employ only one powerscrew 104.

FIG. 7 depicts the cam assemblies 200 at each base 50, other than thebase 50 where the drive mechanism 100 is located. As depicted in FIG. 7, the cam assemblies 200 includes a pair of supports 201. Each support201 includes a top cap 202 and a pair of cams 204. The cams 204 aresecured to the support 201 and include a bearing (not shown) therein toallow for free rotation of the cams 204. The top cap 200 secure the cams204 on the support 201 and may include one or more springs, not shown toallow for the cams 204 to float in the support. Removal of the top cap202 and the upper most of the cams 04 may be necessary for assembly ofthe solar tracker 10 and in particular connection of the torque tube 40to the base 50 and cam assembly 200, as described in greater detailbelow.

On the torque tube 40 at each of the bases 50 is a helical guide device300, depicted in FIG. 7 as formed of two separate components. Thehelical guide device 300 may be formed of steel (e.g., galvanized steel)or another material consistent with the make-up of the torque tube 40 toprevent galvanic action. The helical guide device 300 is may be boltedto the torque tube 40, or adhered with via rivets, adhesives or viawelding or other means known to those of skill in the art.

FIG. 8 provides a plan view of one side of the helical guide device 300attached to the torque tube 40 and secured in the cam assemblies 200.The helical guide device 300 includes a body 302, a plurality of flanges304 which may have holes 306 formed therein for receiving bolts andrivets or the like, and a cam follower 308. The flanges 304 and holes306 may be arranged such that some of the holes 306 mate with a sidewallof the torque tube 40 and others made with a top wall of the torquetube, as shown in FIG. 7 . The cam follower 308 is sized to fit betweenthe two cams 204 located on each support 201, as described above.

The helical guide device 300 may be stamped, forged, press forged, cast,rolled, extruded, or pressed to achieve its final shape as depicted. Onan internal side of the helical guide device 300 (i.e., a side that willface the torque tube 40 when applied thereto) are a plurality of webs310 which provide support and increasing the rigidity of the body 302along its length. In addition, as depicted in FIG. 11 , the cam follower308 may be first stamped to create the shape of the cam follower andthen welded on a backside of the cam follower 308 to increase thestrength and rigidity of the cam follower which, as will be described ingreater detail below absorbs most if not all of the back driving forcesapplied to the solar array 20.

The machining process also achieves the formation of the cam follower308 on the external side of the helical guide device 300. The camfollower 308 is formed in the body 302 of the helical drive device 300such that it defines a helical path along its length. When the torquetube 40 is driven by the drive device 102, the cam follower 308 ridesbetween the two cams 204. As the power screw 104 pushes or pulls on thetorque tube 40, the cam follower 308 forces the torque tube 40 to rotateby acting on the cams 204. Thus, the power screw 104 forces the torquetube 40 to move along its longitudinal axis, and the cam assemblies 200,forces the torque tube 40 to rotate as the cam follower 308 of thehelical guide device 300 slides over the cams 204.

The helical path of the cam follower 308 may include a stow positionportion 312. As depicted in FIG. 10 , the stow position portion 312 is aflat portion of the cam follower 308. As shown, when the torque tube 40of the solar array 22 is driven to the position where the stop positionportion 312 is between the cams 204, the solar array will be in a0-degree position, commonly used to stow solar arrays and solartrackers. That is, the solar array 20 will be substantially parallel tothe ground (e.g., as depicted in FIG. 3 ). In this position, theinteraction of the cams 204 and cam follower 308 allows for forces suchas wind loading to be transmitted from the solar array 20 to the camfollower 308, to the cams 204, and ultimately to the bases 50. Little ifany of the wind loading is then transmitted along the torque tube 40 tobe absorbed by the drive device 100. That is the stow position portion312 works as an anti-backdrive device. When used in conjunction with theinherent anti-backdrive properties of the power screw 104 thecombination substantially prevents the power screw 104 from rotatingwhen an external force is applied to the solar tracking system 10, suchas wind, snow, wildlife, etc.

In the instant figures the stow position portion 312 is depicted asbeing a 0-degree stow position. However, it is contemplated that thestow position portion 312 may be and another angle. For example, in someinstances the stop position for a given solar array 20 may be at30-degrees, 45-degrees, 60-degrees, or any integer value therebetweenwithout departing from the scope of the present disclosure. In thesepositions, some of the force allowed to the solar array 20 will still beabsorbed via the cam follower 308 and cams 204 to reduce the backdriveof the solar array 20 and the drive device 102.

Although generally illustrated as being supported at a geometric centerof rotation, it is contemplated that the solar array 20 may be rotatablysupported at a center of mass. In this manner, the mass of the solararray 20 is balanced about the plurality of bases 50 and the torquerequired to rotate the solar array about the plurality of bases remainssubstantially consistent, with little to no variation in the torquerequired to articulate the solar array 20 through its range or motion.As such, the amount of energy required to articulate the solar array 20is reduced and the various components required to support the solararray 20 may be substantially similar (e.g., no need to design certaincomponents to take a larger load than others), thereby reducing designtime and reducing the number of differing components in the solartracking system 10.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments.

What is claimed is:
 1. A helical guide for use within a solar trackingsystem, comprising: a body extending between a first end portion and anopposite, second end portion and defining a longitudinal axis extendingthrough the first end portion and the second end portion, the bodydefining an inner surface and an opposite, outer surface, each of theinner surface and the outer surface extending between the first endportion and the second end portion, wherein the body is configured to beoperably coupled to an exterior surface of a torque tube; a cam followerdisposed on and extending from the outer surface of the body, the camfollower extending between the first end portion and the second endportion and following a helical path wound about the longitudinal axis,wherein the cam follower is configured to interact with a cam assemblywherein linear movement of the helical guide effectuates rotation of thehelical guide.
 2. The helical guide according to claim 1, wherein thecam follower includes a stow position portion defining an angle of asolar module relative to the ground.
 3. The helical guide according toclaim 2, wherein the stow position portion corresponds to a 0-degreestow position wherein the solar module supported by the torque tube issubstantially parallel to the ground.
 4. The helical guide according toclaim 1, wherein the body of the helical guide is selectively coupled toan exterior surface of a torque tube using mechanical fasteners.
 5. Thehelical guide according to claim 1, further comprising a flange disposedon and extending from the body of the helical guide, the flange defininga hole for receipt of a fastener to selectively couple the helical guideto an exterior surface of a torque tube.
 6. The helical guide accordingto claim 1, wherein a web is disposed on the inner surface of the bodyto provide support to the body.
 7. The helical guide according to claim6, wherein the body, cam follower, and the web are formed as a unitarycomponent.
 8. The helical guide according to claim 7, wherein the web isformed as a separate component from the body and the cam follower. 9.The helical guide according to claim 8, wherein the web is welded to thebody and the cam follower after formation of the body and the camfollower.
 10. The helical guide according to claim 9, wherein the bodyand the cam follower are formed by stamping.
 11. A helical guide for usewith a solar tracking system, comprising: a body defining a longitudinalaxis extending between a first end portion and an opposite, second endportion, the body defining an inner surface and an opposite, outersurface, wherein the inner surface is configured to be operably coupledto an exterior surface of a torque tube; a cam follower disposed on theouter surface of the body and following a helical path extending betweenthe first end portion and the second end portion of the body, whereinthe cam follower defines a top-hat shaped profile that is configured tointeract with a cam assembly wherein linear movement of the helicalguide effectuates rotation of the helical guide.
 12. The helical guideaccording to claim 11, wherein the body and the cam follower are formedby stamping.
 13. The helical guide according to claim 11, wherein thecam follower includes a stow position portion defining an angle of asolar module relative to the ground.
 14. The helical guide according toclaim 13, wherein the stow position portion corresponds to a 0-degreestow position wherein the solar module supported by the torque tube issubstantially parallel to the ground.
 15. The helical guide according toclaim 13, wherein the stow position is a flat portion of the camfollower that is configured to act as an anti-backdrive device toprevent external forces from rotating the helical guide.
 16. A helicalguide for use with a solar tracking system, comprising: a bodyconfigured to be operably coupled to an exterior surface of a torquetube; a cam follower formed separate from and coupled to the body, thecam follower following a helical path extending along a length of thebody, wherein the cam follower is configured to interact with a camassembly wherein linear movement of the helical guide effectuatesrotation of the helical guide, the cam follower defining a stow positionportion defining an angle of a solar module relative to the ground. 17.The helical guide according to claim 16, wherein the stow positionportion corresponds to a 0-degree stow position wherein the solar modulesupported by the torque tube is substantially parallel to the ground.18. The helical guide according to claim 16, wherein the stow positionportion corresponds to an angle selective from the group consisting of30 degrees, 45 degrees, and 60 degrees.
 19. The helical guide accordingto claim 16, wherein the stow position portion is a flat portion of thecam follower that is configured to act as an anti-backdrive device toprevent external forces from rotating the helical guide.
 20. The helicalguide according to claim 16, wherein a plurality of webs is disposed ona surface of the body that is opposite to the cam follower.